Not possible to explicitly select ‘use default behaviour’

If you set a redirect for a given role, and then attempt to revert changes by selecting ‘Select page’, then you don’t get the same behaviour that you had before you set the redirect.

I briefly investigated, and the cause is that there remains an row in the database-table ‘wp_rbrurls_redirect’ with empty values for ‘url_login_dropdown’ and ‘url_login_textbox’.
Could the code of the plugin be modified to either delete these rows, or ignore them when processing a login-attempt?